Tuesday, 25 November 2014

HUMAN EAR: OUTER EAR, MIDDLE EAR, INNER EAR, HEARING

Human Ear has receptors that are sensitive
to the audible frequency range. The audible frequency range for a human ear is
20Hz – 20,000Hz. Human ear is deaf to vibrations which are below 20Hz or above
20,000Hz. This is the ideal range, but exact audible frequency range differs
for each person. A young person may listen as low as 20Hz, but an old man may
not. Age factor has lots of importance in the audible frequency range for a
person.

Structure of Human Ear:

Human ear consists of three parts.

Outer Ear

Middle Ear

Inner Ear

Outer Ear:

Outer ear is the outer part of the ear
which is visible to us. This visible part is made up of cartilage confined by the skin known as the Ear pinna. Many vertebrates, like eyes, can move their pinna in
order to focus on vibrations. Opening of the ear is a tube that leads inwards
called the external auditory meatus.
It has sebaceous organs that produce
secretions. Ear tube collects sound energy and focuses it on the tympanic membrane (eardrum). The
chief function of the outer ear is to direct sound waves toward the tympanic membrane.
Outer ear also contains muscles which have little activity in humans as many
mammals can move their ear to focus sound waves.

Middle Ear:

Middle ear is the part of the ear next to
eardrum. Middle ear is an air filled pit
which communicates with the nasal cavity
(pit of nose) by a thin tube called Eustachian
tube which allows the pressure to level between middle ear and throat. There
are three bones in the middle ear known as incus,
malleus and stapes that fits into the window-like
opening in the bone of the brain that differentiates the middle ear from the
internal ear. These three bones transmit the sound vibrations from the tympanic
membrane (eardrum) into the inner ear. The chief function of the middle ear is
to transmit sound waves from the tympanic membrane to the inner ear. Like outer
ear, inner ear also has muscles and nerves.

Inner Ear:

Inner ear is the inner most part of ear. It
is primarily concerned with detection of sound and balancing. The internal ear comprises
the following parts. There are 3 semicircular
channels having inflammation at one of their closures called the ampullae. These semicircular channels
open into utricles, sacculus and a twisted cochlea.

The auditorynerve which is originating from
brain supplies many branches to the cochlea
making its inward cells delicate to sound vibrations. The three semicircular channel, utricles, sacculus
and cochlea are jointly referred to as membranous
labyrinth. The membranous labyrinth runs
within the bonylabyrinth. A fluid called perilymph
is present between them and inside it, is an alternate liquid the endolymph containing certain calcareous particles.

Hearing:

The sound vibrations circulating in the
atmosphere are directed into the external
auditory meatus. These vibrations strike the tympanic membrane (eardrum) and make it to vibrate. The tympanic membrane
transmits the vibrations to the three
ossicles and then to the perilymph and the endolymph. The calcareous particles in the endolymph hit
the responsive cells of the cochlea
which is stimulated and sends impulses that go through the auditory nerve to mind and are deciphered as sound.

Balancing:

The membranous
labyrinth (3 semicircular channels, utricles, sacculus and coiled cochlea) excluding
cochlea have to do with balancing
and posture. Any flaw in these causes wooziness. It is a basic experience that
if an individual goes all around on a swing, he loses his balance and is not
able to stand upright for quite a while until the balance is reinstated.

Share this post:

Author of This Article,

He is a 18 year old entreprenuer who writes on various topics like SEO, Blogging, Biology and a lot more. Apart from blogging he is also pursuing his career in Medical and Engineering Field. Do Follow him to get in touch.